Karyotype characterization of Mugil incilis Hancock, 1830 (Mugiliformes: Mugilidae), including a description of an unusual co-localization of major and minor ribosomal genes in the family
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Data
2011-03-01
Autores
Hett, Anne Kathrin
Nirchio, Mauro
Oliveira, Claudio [UNESP]
Siccha, Zoila Raquel [UNESP]
Rossi, Anna Rita
Sola, Luciana
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Ictiologia
Resumo
Se presenta la primera descripción del cariotipo de Mugil incilis de Venezuela. El complemento cromosómico está compuesto por 48 cromosomas acrocéntricos uniformemente decrecientes en tamaño. Por lo tanto, los homólogos no pueden ser claramente identificados, con excepción de uno de los pares de mayor tamaño, clasificado como número 1, cuyos homólogos poseen una constricción secundaria subcentromérica, y el par de cromosomas número 24, considerablemente más pequeño que los otros. El bandeo-C reveló bloques heterocromáticos en las regiones centroméricas/pericentroméricas de todos los cromosomas, más conspicuas en el cromosoma 1 en el que las señales C-positivas se encuentra localizada precisamente en la constricción secundaria. La tinción con AgNO3 y la Hibridación Fluorescente in situ (FISH) con sonda 45S rDNA revelaron que las regiones organizadoras del nucléolo están ciertamente localizadas sobre la constricción secundaria del cromosoma número 1. FISH con 5S rDNA reveló que los genes ribosomales menores están ubicados en este mismo par cromosómico, en posición proximal a las NORs, aunque cercanas al centrómero y de menor tamaño en comparación con los clúster de genes ribosomales mayores. Ésta es la primera descripción de co-localización de genes ribosomales mayores y menores en la familia Mugilidae. Los datos se discuten bajo perspectivas citotaxonómicas y filogenéticas.
This study reports the description of the karyotype of Mugil incilis from Venezuela. The chromosome complement is composed of 48 acrocentric chromosomes, which uniformly decrease in size. Therefore, the homologues can not be clearly identified, with the exception of one of the largest chromosome pairs, classified as number 1, whose homologues may show a subcentromeric secondary constriction, and of chromosome pair number 24, which is considerably smaller than the others. C-banding showed heterochromatic blocks at the centromeric/pericentromeric regions of all chromosomes, which were more conspicuous on chromosomes 1, given the C-positive signals include the secondary constrictions. AgNO3 and fluorescent in situ hybridization (FISH) with 45S rDNA demonstrated that the nucleolus organizer regions are indeed located on the secondary constrictions of chromosome pair number 1. FISH with 5S rDNA revealed that the minor ribosomal genes are located on this same chromosome pair, near the NORs, though signals are closer to the centromeres and of smaller size, compared to those of the major ribosomal gene clusters. This is the first description of co-localization of major and minor ribosomal genes in the family. Data are discussed from a cytotaxonomic and phylogenetic perspective.
This study reports the description of the karyotype of Mugil incilis from Venezuela. The chromosome complement is composed of 48 acrocentric chromosomes, which uniformly decrease in size. Therefore, the homologues can not be clearly identified, with the exception of one of the largest chromosome pairs, classified as number 1, whose homologues may show a subcentromeric secondary constriction, and of chromosome pair number 24, which is considerably smaller than the others. C-banding showed heterochromatic blocks at the centromeric/pericentromeric regions of all chromosomes, which were more conspicuous on chromosomes 1, given the C-positive signals include the secondary constrictions. AgNO3 and fluorescent in situ hybridization (FISH) with 45S rDNA demonstrated that the nucleolus organizer regions are indeed located on the secondary constrictions of chromosome pair number 1. FISH with 5S rDNA revealed that the minor ribosomal genes are located on this same chromosome pair, near the NORs, though signals are closer to the centromeres and of smaller size, compared to those of the major ribosomal gene clusters. This is the first description of co-localization of major and minor ribosomal genes in the family. Data are discussed from a cytotaxonomic and phylogenetic perspective.
Descrição
Palavras-chave
C-banding, COI, 5S rDNA, Mullet, NORs
Como citar
Neotropical Ichthyology. Sociedade Brasileira de Ictiologia, v. 9, n. 1, p. 107-112, 2011.